The cardiologist convicted of involuntary manslaughter in Michael Jackson’s death called his mistress while riding in the ambulance taking the singer to the hospital — evidence he may have requested help in covering his tracks, it was revealed Wednesday.

Los Angeles Police Det. Orlando Martinez said cell phone records show Dr. Conrad Murray called his girlfriend, Nicole Alvarez, at 1:08 p.m. on June 25, 2009, a minute after the ambulance carrying him and his stricken mega-star patient left Jackson’s home for Ronald Reagan UCLA Medical Center.

“Do you have an opinion as to the substance of that call?” Brian Panish, a lawyer representing Jackson’s mother and children in their negligence lawsuit against concert promoter AEG, asked Martinez.

“Yes,” the lawman replied, explaining that he had interviewed Alvarez and served a search warrant at her Santa Monica address.

“What was determined?” Panish asked.

“I found one piece of paper with Dr. Murray’s name — that had fallen behind the door of a cabinet — in the entire apartment (where) he’d been staying at (for) at least two months,” Martinez replied.

Panish asked whether he found that suspicious.

“Yes,” Martinez replied. “He was living there, and none of his stuff was there.”

Prior criminal proceedings against Murray revealed the doctor — convicted at trial in 2011 — had pharmacy shipments sent to Alvarez’s address.

Martinez was the second witness called before the jury of six men and six women in Los Angeles County Superior Court for the civil case in which the Gloved One’s family argues that AEG, promoter of Jackson’s ill-fated comeback tour, had a hand in his drug-fueled demise.

Katherine Jackson, 82, did not attend the shortened third day of testimony, which only lasted an hour due to a juror’s request to attend a funeral.

Her lawyer said she also planned to sit out upcoming testimony from coroner’s office officials because the evidence promises to be graphic.

CARL DE SOUZA/AFP/Getty Images

Murray was convicted in 2011 of involuntary manslaughter in Michael Jackson’s overdose death.

“She doesn’t need to hear that,” Panish told the Daily News. “We’re not trying to get sympathy.”

Martinez told jurors his investigation led him to conclude that Murray was deep in debt at the time of the “Thriller” singer’s overdose death, giving him a financial motive to provide the surgery-strength anesthetic Propofol as a treatment for insomnia, despite recommendations to the contrary. Jackson died from acute Propofol intoxication, an autopsy found.

On Tuesday, Martinez told jurors that Murray was about to lose his home to foreclosure and was roughly $500,000 in debt when he negotiated a $150,000-per-month agreement to act as Jackson’s personal physician for the AEG-backed “This Is It” comeback concert series.

Martinez covered more financial ground in testimony Wednesday, saying Murray had a history of unpaid rent on his Las Vegas office and was delinquent in paying his taxes.

“(It’s) just some more evidence of him being in financial dire straits,” Martinez said.

He said police also ran credit reports on Murray.

“If anyone would have run the credit report, they would have got the same information?” Panish asked.

“Yes,” Martinez said.

Katherine Jackson’s lawsuit claims AEG should be held accountable for hiring Murray without a background check and negligently supervising him.

AEG denies any wrongdoing, saying Michael Jackson personally hired Murray and kept his Propofol use a closely guarded secret.

After the jury left the courtroom Wednesday, Katherine Jackson’s lawyers said they believed they could locate Michael’s longtime nanny and confidante, Grace Rwaramba, and plan to call her as a witness as the trial proceeds.

“We couldn’t find her, no one could find her,” lawyer Kevin Boyle said of the last-minute addition. “But we think we’re going to be able to find her, hopefully.”

Murray is currently serving a four-year prison sentence.

ndillon@nydailynews.com